Skilsaw, handsaw, large framing square, hammer, nails and a calculator comes in handy. Measure total height from floor to floor and divide by the number of risers you think you need. Trial and error will get you to a riser height of no more than 8", preferrably around 7". Average it out until each riser is of equal height. Tread length should be around 11". You will have one less tread than total number of risers. Total number of treads will give total horizontal distance of stairs. Use the framing square to mark off risers and treads along a length of 2x12. Skilsaw is used to make the bulk of each cut and handsaw to finish each cut. Stair layout and construction is one of the more difficult carpentry tasks, but perhaps this will get you started.